1. Field of the Invention
The subject invention relates to doors and to emergency exits, to revolving doors and, more specifically, to the provision of emergency exits through revolving doors.
2. Information Disclosure Statement
The following disclosure statement is made pursuant to the duty of disclosure imposed by law and formulated in 37 CFR 1.56(a). No representation is hereby made that information thus disclosed in fact constitutes prior art, inasmuch as 37 CFR 1.56(a) relies on a materiality concept which depends on uncertain and inevitably subjective elements of substantial likelihood and reasonableness and inasmuch as a growing attitude appears to require citation of material which might lead to a discovery of pertinent material though not necessarily being of itself pertinent. Also the following comments contain conclusions and observations which have only been drawn or become apparent after conception of the subject invention or which contrast the subject invention or its merits against the background of developments which may be subsequent in time or priority.
Revolving doors have been used for a long time as a convenient means for providing routine access to and egress from buildings, while preserving the desired inside temperature of the building against the cold in winter and the heat in summer and other seasonal fluctuations. Compared to a regular swinging or sliding door, revolving doors tend to be rather bulky, having a width on the order of their height. Also, traditional revolving doors tend to be unsafe in a panic, where people exiting a building during a fire or other emergency may work against each other on different leaves of a revolving door. In consequence, fire safety and other regulations usually require the provision of a swinging-type emergency exit adjacent to each revolving door. The inherent bulk of a revolving door is thus in practice aggravated by the need of a separate emergency exit, which further increases the needed width of a revolving door installation.
In recent years, proposals have arisen to construct leaves of revolving doors in a breakaway fashion, permitting panicked people or others trying to exit a building in an emergency, to fold leaves of a revolving door in the direction of their desired exit through the revolving door enclosure.
One problem with such proposals has been their need for an almost impossible compromise. On the one hand, the breakaway feature has to be such that people attempting to exit the building in an emergency could really break the revolving door leaves loose without undue resistance. On the other hand, care had to be taken that normal causes, such as the air pressure differential between the inside and outside of an air conditioned building, would not actuate the breakaway feature.
In practice, this compromise was difficult to reach, and there were many instances where revolving door leaves either broke loose during normal operation or, contrariwise, were difficult to align with the exit traffic in an emergency.
Some control over this situation was obtained with the aid of magnetic locks having one part, such as the wound armature, associated with a turnstyle, defining the mutual angular position of the revolving door leaves, and having the other part, such as a striker plate, associated with a revolving door leaf. In practice, two or more of the door leaves were equipped with magnetic locks which held the door leaves in their respective angular position during normal operation of the revolving door. In case of an emergency, such as manifested by the signal of a smoke detector, the magnetic locks were deenergized, whereby the door leaves became loose and could be moved into the direction of the main exit traffic by people leaving the building in an emergency.
This, however, left the door leaves in an uncertain position liable to confuse some people. The idea thus arose to provide a solenoid-actuated ratchet drive for stepping the loose door leaves to the direction of main exit traffic. This was, however, also not acceptable from a security point of view.
An overriding problem in this area is that fire officials and building safety people are very concerned about the heavy losses attributed to revolving doors in fire disasters going back for decades and including the terrible fire at the Coconut Grove night club in Boston, where close to 500 people perished some forty years ago, when the panicky crowd jammed the revolving doors in an attempt to escape the disaster. Accordingly, solutions and advances in the art of the highest order are required for a realization of any endeavor to provide for emergency exits through revolving doors.